$ git pull
fatal: unable to access 'https://github.com/fincher42/demo.git/': Received HTTP code 407 from proxy after CONNECT
The proxy is complaining that the password is out of date by giving us a 407 error, which is an authentication error. Then I remember I just changed my system password.
The solution is easy, just tell Git your new password:
git config --global http.proxy http://myUserId:myPassword@myProxy.myDomain.com:80
git config --global https.proxy https://myUserId:myPassword@myProxy.myDomain.com:80